inline fan for long furnace run?

timber

I've got a long run from our furnace to our front two bedrooms at the front of our home and the furnace is at the back. I'm working on insulation issues in the walls, but will an inline fan help bring a little more heat into these rooms? I've done about all I can do to adjust other rooms where not as much heat is needed, but the bedrooms really need some more. By the time the air gets to those rooms , it's cooled considerably. Any thoughts would be greatly appreciated

Sammy

Assuming the ductwork is sized accordingly, a fan should not be needed.

If the ducts run thru an unheated space, I would take a look at it to see if it needs some patching on any joints that may be leaking or possibly adding insulation to the ductwork to keep it from cooling off.